Neurological disorders found to be biggest cause of poor health

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Nervous system diseases such as stroke, dementia and migraines are the biggest causes of poor health globally, affecting billions of people and hitting poorer countries hardest, a wide-ranging new study shows.

Research published in The Lancet Neurology on Thursday said that despite improvements in prevention and treatment, more than 40% of the global population will still suffer from neurological problems in 2021.

The paper highlights the dramatic increase in the number of people affected by neurological diseases as one result of increased life expectancy.

“The global neurological burden is growing rapidly and will put greater pressure on health systems in the coming decades,” said Dr. Valery Feigin, co-author of the paper and director of the National Stroke and Applied Neuroscience Institute at the University of Auckland. “However, many current strategies to reduce neurological disease are ineffective or under-deployed.”

The study used data from 204 countries and regions and found that 3.4 billion people were living with neurological diseases in 2021. This has led to an increase in the number of disability-adjusted life years (Dalys), a measure of disability, illness and the impact of premature babies. The number of deaths due to neurological problems has increased from 375 million in 1990 to 443 million in 2021.

This growth is driven by population growth and longer lifespans. Once adjusted for this demographic change, the Daly index due to neurological disease fell by 27% and deaths by 34% over the 31-year survey period. Researchers say this partly reflects the success of vaccinations and other prevention methods against diseases such as tetanus, meningitis and stroke.

Researchers found that the 10 biggest causes of neurological health loss in 2021 are stroke, neonatal brain injury, migraines, Alzheimer's and other dementias, diabetes-related nerve damage, meningitis, epilepsy, Neurological complications from prematurity, autism spectrum disorders, and neurological cancers.

The most common disorders are tension-type headache and migraine, with more than 3 billion cases combined.

The paper reveals stark contrasts between rich and poor countries. Daly disease and mortality rates are five times higher in West and Central Africa than in high-income countries in Asia and Australia.

Another study co-author, Dr. Tarun Dua, said neurological problems disproportionately affect poorer countries, in part because of higher rates of conditions affecting newborns and children under five, particularly birth-related complications and infections.

“Increased infant survival has led to an increase in long-term disability, while limited access to treatment and rehabilitation services has led to a significant increase in the proportion of deaths in these countries,” said Dua, head of the World Health Organization's brain health unit.

Because many neurological diseases have no cure, researchers urge greater emphasis on prevention. Among their recommended measures are efforts to lower blood pressure, reduce lead exposure and reduce high blood sugar levels.

Neuroscientist Michael Zandi, who was not involved in the paper, said the investigation is important because it highlights the prevalence of a disease that has historically been often stigmatized and understudied.

“It's important to recognize how widespread these diseases are,” said Zandi, a researcher at University College London's Queen Square Institute of Neurology. “They involve people of all ages — including a lot of people with disabilities.”

Professor Wolfgang Grissold, president of the World Federation of Neurology, who was also not involved in the study, said further research should look at the impact of neuromuscular diseases, cancers of the nervous system and neuropathic pain.